Vehicle seat with cushion plate

ABSTRACT

A vehicle seat comprises a rectangular-shaped seat back frame having right and left side frames; a flexible plate member provided between the right and left side frames; a seat back cushion provided in front of the flexible plate member; a mechanism for pushing the seat back cushion to a front direction by forwardly protruding the flexible plate member that results from the flexible plate member being bent; a headrest for supporting a head of a seat occupant, wherein the headrest is forwardly movably connected to the right and left side frames via right and left link members; and a rear-end collision detecting plate disposed at a portion of the seat back frame behind the seat occupant, wherein the rear-end collision detecting plate detects rearward movement of the seat occupant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 12/707,095, filed Feb. 17, 2010, which is a divisionalapplication of U.S. patent application Ser. No. 11/718,309, filed Nov.21, 2007, which is a PCT national stage entry of international patentapplication no. PCT/JP2005/19937, filed Oct. 28, 2005, which claims theforeign priority benefit of Japanese patent application no.JP2004-313623, filed Oct. 28, 2004. The contents of these applicationsare herein incorporated by reference.

TECHNICAL FIELD

The present invention relates to a vehicle seat, and particularly to avehicle seat having a cushion plate with a pressure adjusting mechanism.

BACKGROUND

A conventional seat back cushion for a vehicle seat is resilientlysupported by means of a number of seat springs which are located betweenside frames of a seat back frame. The seat springs generally comprisezigzag springs or formed wire springs.

The degree of bending of the seat springs locally vary depending on themagnitude of load imparted. The springs located in the upper and lowerportions of the seat back frame are more bent than those located in thecentral portion of the seat back frame. Even in one spring, the centralpart of the spring is more bent than the right and left side parts ofthe spring. Thus, the degree of bending of the springs are locallyvaried. This brings about deterioration of the stability and comfort ofthe seat when a person sits on the seat.

Japanese Patent Application Laid-Open No. 11-206506 discloses astructural arrangement where an auxiliary plate, which is forwardly andrearwardly movable, is provided in connection with the cushion plate.

The auxiliary plate disclosed in Japanese Patent Application Laid-OpenNo. 11-206506 is integrally formed at the central part of the cushionplate, and the cushion plate is disposed only around the auxiliaryplate. Therefore, the cushion plate disposed around the auxiliary platefails to exhibit its function as the mechanism for resilientlysupporting the seat back cushion. This means that a load of the seatedperson is focused on the auxiliary plate and is not effectivelydispersed in the cushion plate.

Also in the conventional technique, it is difficult to provide both of apressure adjusting mechanism of the cushion plate and an active headrestmechanism for moving the headrest to the front when the vehicle rear-endcollision occurs in the seat back. In other words, the pressureadjusting mechanism lowers a sensitivity of a collision detector of theactive headrest mechanism, and hence, it is difficult to coexistentlyprovide both of the mechanisms.

SUMMARY

Accordingly, an object of various embodiments of the present inventionis to provide a cushion plate with a pressure adjusting mechanism whichis able to support the seated person while effectively dispersing theload of the seated person.

Another object is to provide a vehicle seat having a cushion plate witha pressure adjusting mechanism and an active headrest mechanism formoving the headrest to the front when the vehicle rear-end collisionoccurs.

In more detail, various embodiments of the invention provide a vehicleseat comprising: a seat back frame; a headrest for supporting a head ofa seat occupant, wherein the headrest is forwardly movably connected tothe seat back frame; a rear-end collision detector mounted to the seatback frame at a position behind the seat occupant, wherein the rear-endcollision detector detects rearward movement of the seat occupant andmoves rearward; and the rear-end collision detector is operativelyconnected to the headrest such that the rearward movement of therear-end collision detector forwardly moves the headrest; a headrestsupport for supporting the headrest that extends in a horizontaldirection, wherein the headrest support is movably connected to a sideframe that constitutes a side portion of the seat back frame through alink member; a bracket mounted to the side frame, wherein a link supportshaft is mounted to the bracket and wherein the link member is movablymounted to the link support shaft; a front extending portion inwardlyextending in a right-to-left direction and formed at a front end of alateral face of the side frame; and a rear extending portion inwardlyextending in the right-to-left direction and formed at a rear end of thelateral face of the side frame; wherein: a concave portion is formed ata portion of an inner end portion of the front extending portion of theside frame that faces at least a part of the bracket; and the concaveportion is disposed at a position facing the link support shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings illustrate an embodiment of the invention that isdescribed in more detail below.

FIG. 1 is a perspective view showing a vehicle seat;

FIG. 2 is an exploded perspective view showing a seat back frame of thevehicle seat and basic components of an active headrest mechanism;

FIG. 3 is a perspective view showing an assembly of the components shownin FIG. 2;

FIG. 4 is a perspective view showing a state that a cushion plate and anauxiliary plate are mounted to the assembly of FIG. 3;

FIG. 5 is a side view showing a side frame of the seat back frame andthe basic components of the active headrest mechanism;

FIG. 6 is a perspective view showing the back sides of the cushion plateand the auxiliary plate;

FIG. 7 is a side view showing a relationship between a part of skeletonof a seated person and the cushion plate; and

FIG. 8 is a longitudinal sectional view showing the cushion plate andthe auxiliary plate.

DETAILED DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention will be described with referenceto the accompanying drawings. Referring to FIGS. 1-4, a vehicle seat 1of the present invention has a seat back 2, a seat bottom 3 and aheadrest 4 provided at the top of the seat back 2. Referring to FIGS. 2and 3, a seat back frame 5 of the seat back 2 includes a pair of sideframes 6, an upper frame 7 and a lower frame 8, and has a substantialrectangular shape.

A headrest support 10 is arranged near the upper frame 7. The support 10horizontally extends and is movable with respect to the seat back frame5. Lower parts of pillars 9 of the headrest 4 are inserted into verticalengaging parts 11 which are fixed to the headrest support 10. Thepillars 9 are vertically adjustable with the aid of the verticalengaging parts 11.

Upper brackets 12 are fixed to the side frames 6, respectively. Theframes 6 comprise a front projecting wall (front extending portion) 6 b,a rear projecting wall (rear extending portion) 6 c, an opening 6 d, aninwardly protruding portion 6 e, a lateral face 6 f, a concave portion 6g, which may be a cutout portion formed at a portion of an inner endportion 6 h of the front projecting wall (front extending portion) 6 bof the side frame 6 that faces at least a part of the bracket 12, wherethe concave portion 6 g is disposed at a position facing a link supportshaft 16.

An upper link (link member) or bell crank 15 is rotatably mounted toeach upper bracket 12 by a shaft 16 that protrudes through a first hole16 a of the upper link 15 at a link support portion 15 a. Each upperlink 15 includes an upper long arm 22 extending upward and a lower shortarm 23 extending downwardly and to the front side. The upper link 15 isurged by resiliency of an upper spring 13 clockwise, as shown in FIG. 5.The upper spring 13 includes a first end coupled to the upper link 15and a second end coupled to the side frame 6. The right and left ends ofthe headrest support 10 are coupled to the upper arms 22, respectively.Each lower arm 23 is axially fixed to the upper part of a longitudinallyextending coupling (or load transmission) rod 20 by way of a pin 21 thatextends through a second hole 21 a of the upper link 15.

The upper link 15 is normally held at a position indicated by a solidline in FIG. 5 by the resiliency of the upper spring 13 or the like,whereby the headrest 4 is also held at a normal position. However, whenthe upper link 15 is rotated counterclockwise toward a positionindicated by a dotted line, the headrest support 10 forwardly moves andthe headrest 4 is pushed to the front.

A horizontally extending vehicle rear-end collision detector 25 isarranged between the side frames 6, 6. The collision detector 25comprises a contact portion 25 a, and a reinforcing portion 25 b (bead).When a rear-end collision occurs and the vehicle seat 1 relatively movesforward against the vehicle seat occupant T (FIG. 7), the collisiondetector 25 (FIGS. 3, 4) moves rearward by being pushed by the seatoccupant T. Both ends of the collision detector 25 are coupled to lowerlinks 26, 26 by way of pins 27, 27 (also “swinging shaft” or “connectingshaft”) which are axially fixed to the side frames 6, 6 by link supportshafts 28, 28, via connecting members 25′, 25′ respectively. A lowerbracket 35 is provided having a link shaft supporting face 35 a, a firstattachment portion 35 b, and a second attachment portion 35 d. The lowerbracket 35 may attach via a bracket attachment portion 35 c. Theconnecting members 25′ each comprise a bend portion 25′a and astrengthening portion 25′b. The lower part of the coupling rod 20 iscoupled to the lower link (link member) 26 by way of a pin 29. As shownin FIG. 5, one end of a lower spring (biasing member) 14 is coupled tothe lower link 26 at a first biasing member engagement portion 26′,while the other end thereof is coupled to the side frame 6 at a secondbiasing member engagement portion 6″, whereby the lower links 26 areurged counterclockwise. As a result, the collision detector 25 is heldat a normal position, located in the front side.

When a rear-end collision occurs, the vehicle rear-end collisiondetector 25 is pushed by the seat occupant T to move rearward and toturn the lower links 26 counterclockwise in FIG. 5 and to lower thecoupling rod 20. At this time, a distance between the pin 29 and theshaft 28 is shorter than a distance between the pin 27 and the shaft 28,so that a backward movement of the collision detector 25 is efficientlytransmitted to the coupling rod 20. A downward movement of the rod 20rotates the upper link 15 counterclockwise so that the headrest support10 moves forward. The upper arm 22 of the upper link 15 is longer thanthe lower arm 23 so that the downward movement of the coupling rod 20efficiently causes the headrest support 10 to move forward. The forwardmovement of the headrest support 10 pushes the headrest 4 to the front,thereby protecting a head (neck) of the seat occupant T at the time ofthe rear-end collision.

The side frames 6 are formed with a metal plate having a predeterminedwidth as viewed in the front-and-back direction. A transmissionmechanism for transmitting a backward movement of the vehicle rear-endcollision detector 25 to the headrest support 10 is located at aposition near the side frames 6. Accordingly, a cushion 17 of the seatback 2 does not interfere with a motion of the transmission mechanism. Amechanism ranging from the collision detector 25 to the headrest support10 forms an active headrest mechanism.

A flexible plate member 30 comprises a flexible cushion plate 31 and aflexible auxiliary plate 41. The flexible cushion plate 31 is arrangedinside the seat back frame 5. The cushion plate 31 is preferably made ofsynthetic resin such as polypropylene, and is substantially a singlerectangular plate. The cushion plate 31 is attached to seat springs 32such as zigzag springs or formed wire springs at mounting portions (wireengagement portions) 31 a, 31 a′ that may include a rearward projectingportion 31 b. The cushion plate 31 has a first plate portion 31 d. Theseat springs 32 include at least an upper seat spring/wire member 32Aand a lower seat spring 32B, the lower seat spring 32B being attached tothe cushion plate 31 at a mounting portion 31 a′ within a protrudingportion 31 c, and to the side frame 6 at a wire spring engagementportion 6 a′. The seat springs 32 horizontally extend and arerespectively coupled to the side frames 6 of the seat back frame 5 atwire spring engagement portions 6 a, 6 a′. The seat back cushion 17 isprovided in front of the cushion plate 31.

When the flexible cushion plate 31 receives a load from the seatoccupant T, the cushion plate 31 moves rearward against the elasticityof the seat springs 32 and flexibly supports the seat occupant T. Thecushion plate 31 supports the seat back cushion 17 in “plane”.Therefore, the cushion plate makes the seat occupant T feel more stableand comfortable than the conventional one in which the seat back cushion17 is supported by only the seat springs 32.

An upper edge 34 of the flexible cushion plate 31, as shown in FIG. 7,is located somewhat higher than the ninth thoracic vertebra X of theseat occupant T of the average height. The center gravity of the upperbody of the seat occupant T is positioned near the ninth thoracicvertebra X. The cushion plate 31 is able to effectively support a partaround the center of gravity of the seat occupant T.

The upper seat spring 32A is selected to be at substantially the sameheight level as the ninth thoracic vertebra X or somewhat lower than it.In FIG. 7, the upper seat spring 32A is located somewhat lower than theninth thoracic vertebra X. The reason for this is that a load of theupper part of the body to the seat back cushion 17 usually acts on therearward side.

The flexible cushion plate 31 includes a lower part 33 for supporting aportion near the sacrum S of the pelvis. The lower part 33 enhances aholding property at a portion near the hip of the seat occupant T.

The vehicle rear-end collision detector 25 is located in the rear of theflexible cushion plate 31 in a state that a predetermined space ispresent therebetween. Since the cushion plate 31 takes a plate-likeshape for broadly covering the back of the seat occupant T, the flexiblecushion plate 31 receives a load of the seat occupant T on a wide areawhen a rear-end collision occurs, and moves rearwardly. The amount of arearward movement of the flexible cushion plate 31 is the largestbetween a mid portion as vertically viewed and a portion somewhat lowerthan the mid position. Therefore, the collision detector 25 ispreferably located at a mid position as vertically viewed or a positionsomewhat lower than the mid position in order to reliably receive therearward movement of the cushion plate 31. Since a width of the seatback 2 as viewed in the front-and-back direction becomes narrowerupward, it is not preferable that the collision detector 25 is locatedat an upper position on the rear side of the flexible cushion plate 31.

A flexible auxiliary plate 41 is provided between the flexible cushionplate 31 and the seat back cushion 17. Collectively, the flexiblecushion plate 31 and auxiliary plate 41 may be construed as a loadreceiving member. The auxiliary plate 41 is preferably made of syntheticresin such as polypropylene, and is substantially a single rectangularplate, which is smaller than the flexible cushion plate 31. When theauxiliary plate 41 is operated by the seat occupant T, it is bent to thefront and pushes the seat back cushion 17 forwardly, thereby adjusting acushion pressure against the seat occupant T.

The auxiliary plate 41, which has a top portion (or a maximum forwardcurve portion) 41 a, is provided with rearward projecting upper sliders42 and lower sliders 43. The upper sliders 42 protrude in a rearwardprojecting portion 42 a to the rear side of the flexible cushion plate31 through vertical upper slits 45 formed in the cushion plate 31. Thelower sliders 43 protrude to the rear side of the cushion plate 31through vertical lower slits 46 formed in the cushion plate 31. An upperhorizontal mounting shaft 48 is bridged between the upper sliders 42 and42, and a lower horizontal mounting shaft 49 is bridged between thelower sliders 43 and 43.

The auxiliary plate 41 is mounted to the cushion plate 31 by using themounting shafts 48 and 49. The sliders 42 and 43 are vertically slidablein the slits 45 and 46, respectively. When the upper sliders 42 aremoved downwardly and the lower sliders 43 are moved upwardly, theauxiliary plate 41 is bent to the front.

An upper U-shaped bracket 51 is rotatably mounted on the upperhorizontal mounting shaft 48. The bracket 51 includes a pair of arms 52mounted to the mounting shaft 48 and a coupling part 53 provided betweenthe arms 52. A cable head 56A of an inner cable 56 of a wire cable 55 isplaced on and secured to the coupling part 53. A lower bracket 66 isrotatably mounted to the lower horizontal mounting shaft 49. The lowerbracket 66 includes a pair of arms 67 mounted to the mounting shaft 49and a coupling part 68 provided between the arms 67. A tube head 57A ofan outer tube 57 of the wire cable 55 is placed on and secured to thelower bracket 66. The other end of the wire cable 55 is coupled to anoperation member 58 provided on the vehicle seat 1.

When the operation member 58 is operated, a distance between the cablehead 56A and the tube head 57A, i.e., a distance between the uppersliders 42 and the lower sliders 43 is adjusted. When the distancebecomes long, the auxiliary plate 41 is parallel to the flexible cushionplate 31, and when it becomes short, the auxiliary plate 41 bends toproject to the front. Thus, by operating the operation member 58, adegree of bending (forward projecting quantity) of the auxiliary plate41 can be adjusted.

The auxiliary plate 41 includes a thin part 60 for defining a curvedshape of the auxiliary plate 41. When the distance between the uppersliders 42 and the lower sliders 43 becomes short, the auxiliary plate41 is curved with respect to the thin part 60. Accordingly, the curvedshape of the auxiliary plate 41 is kept in a predetermined shape, andthe cushion pressure adjustment by the auxiliary plate 41 is madeeffective by setting the thin part 60 at the lumber part of the seatoccupant T.

A spring 61, having an upper end attaching portion 61 a for urging theupper horizontal mounting shaft 48 upwardly is provided between theupper horizontal mounting shaft 48 and the flexible cushion plate 31 (orthe upper seat spring 32A).

The flexible cushion plate 31 bends under a load from the seat occupantT and moves rearward against the elasticity of the seat springs 32, andflexibly supports the seat occupant T. The flexible cushion plate 31supports the seat back cushion 17 in “plane”. Therefore, the cushionplate makes the seat occupant T feel more stable and comfortable thanthe conventional one in which the seat back cushion 17 is supported byonly the seat springs 32.

When a physique of the seat occupant T presents an insufficient pressurefrom the seat back cushion 17, the seated person pulls the inner cable56 by operating the operation member 58 to reduce the distance betweenthe upper sliders 42 and the lower sliders 43. Then, the auxiliary plate41 protrudes forward with respect to the thin part 60, pushes the seatback cushion 17 forward to increase the cushion pressure, whereby thecushion pressure is adjusted as the seat occupant T desires.

When the auxiliary plate 41 is curved by the operation member 58, thecushion pressure is changed. Since the auxiliary plate 41 and theflexible cushion plate 31 are in overlapping relation, the load by theseat occupant T that the auxiliary plate 41 receives is directlydispersed into the flexible cushion plate 31 as a single large plate.Accordingly, the good stability and comfort of the seat back cushion 17are not lost.

When a rear-end collision occurs, the flexible cushion plate 31 greatlymoves rearward by the load from the seat occupant T to come into contactwith the vehicle rear-end collision detector 25 and to move it backward.In turn, the lower links 26, in FIG. 5, rotate counterclockwise to lowerthe coupling rod 20. The downward movement of the coupling rod 20 turnsthe upper links 15 counterclockwise to move the headrest support 10 tothe front. As a result, the headrest 4 pushed to the front to protectthe head (neck) of the seat occupant T against the impact by therear-end collision.

In this case, the distance between the pin 29 and the shafts 28 isshorter than that between the pins 27 and the shafts 28. Accordingly,the lower links 26 efficiently transmits the rearward movement of thecollision detector 25 to the coupling rod 20. Since the upper arms 22 ofthe upper links 15 are longer than the lower arms 23, the downwardmovement of the coupling rod 20 is efficiently transmitted to theheadrest support 10. Therefore, the forward movement of the headrest 4is satisfactorily secured.

Since the cushion plate 31 is shaped like a plate broadly covering theback of the seat occupant T, it reliably receives the rearward movementof the seat occupant T at the time of the rear-end collision in a broadarea to reliably transmit the rearward movement of the seat occupant Tto the collision detector 25.

When the auxiliary plate 41 is bent by the operation member 58, thecushion pressure is changed. Since the flexible cushion plate 31 isshaped like a plate broadly covering the back of the seat occupant T,and receives the load from the seat occupant T in a dispersing manner,the change of the cushion pressure by the auxiliary plate 41 does notsubstantially move the positions of the flexible cushion plate 31 andthe collision detector 25. Accordingly, the relative position of thecushion plate 31 to the collision detector 25 is retained and the changeof the cushion pressure by the auxiliary plate 41 does not substantiallyinterfere with the function of the active headrest mechanism.

TABLE OF REFERENCE CHARACTERS

-   1 vehicle seat-   2 seat back-   3 seat bottom-   4 headrest-   5 seat back frame-   6 side frame-   6 a, 6 a′ wire spring engagement portions-   6 b side frame front projecting wall-   6 c side frame rear projecting wall-   6 d opening-   6 e protruding portion-   6 f lateral face-   6 g concave (cutout) portion-   6 h inner end portion-   6″ second biasing member engagement portion-   7 upper frame-   8 lower frame-   9 pillars-   10 headrest support (also “lateral member”)-   11 vertical engaging parts-   12 upper bracket-   13 upper spring-   14 lower spring (also “biasing member”)-   15 upper link (also “link member”)-   15 a link support portion-   16 link support shaft-   16 a first hole of upper link-   17 cushion-   20 longitudinally extending coupling rod (or “load transmission    rod”)-   21 pin-   21 a second hole of upper link-   22 upper link upper (second) long arm-   23 upper link lower (first) short arm-   25 rear-end collision detector-   25 a contact portion-   25 b reinforcing portion (bead)-   25′ connecting member-   25′a bend portion-   25′b strengthening portion-   26 lower link (also “link member”)-   26′ first biasing member engagement portion-   27 pin (also “swinging shaft” or “connecting shaft”)-   28 link support shaft-   29 pin-   30 flexible plate member-   31 flexible cushion plate-   31 a, 31 a′ mounting portions (also “wire engagement portions”)-   31 b projecting portion-   31 c protruding portion-   31 d first plate portion-   32 seat springs-   32A upper seat spring/wire member-   32B lower seat spring-   33 lower part of flexible cushion plate-   34 upper edge of flexible cushion plate-   35 lower bracket-   35 a link shaft supporting face-   35 b first attachment portion-   35 c bracket attachment portion-   35 d second attachment portion-   41 flexible auxiliary plate-   41 a top portion (maximum forward portion of a curve) of auxiliary    plate-   42 rearward projecting upper slider-   42 a rearward projection portion (“retainer”)-   43 lower slider-   45 vertical upper slit-   46 vertical lower slit-   48 upper horizontal mounting shaft (also “linear member”)-   49 lower horizontal mounting shaft-   51 upper U-shaped bracket-   52 arms-   53 coupling part-   55 wire cable-   56 inner cable-   56A cable head-   57 outer tube-   57A tube head-   58 operation member-   60 auxiliary plate thin part-   61 spring-   61 a spring upper end attaching portion-   66 lower bracket-   67 lower bracket arm-   68 coupling part-   T occupant

1. A vehicle seat comprising: a seat back frame having right and leftside frames; a headrest forwardly movably mounted to the seat backframe; a rear-end collision detector mounted to the seat back frame,wherein the rear-end collision detector detects rearward movement of theseat occupant and moves rearward; and the rear-end collision detector isoperatively connected to the headrest such that the rearward movement ofthe rear-end collision detector forwardly moves the headrest to supporta head of a seat occupant; a respective support shaft mounted to eachside frame; a support member that supports the support shaft; a linkmember mounted to the support shaft; and a biasing member that biasesthe link member; wherein: a lower portion of the link member isconnected to the rear-end collision detector; each of the side frames isprovided with a front projecting wall inwardly projecting and integrallyformed at a front end of the respective side frame, and a rearprojecting wall inwardly projecting and integrally formed at a rear endof the respective side frame; each of the side frames comprises alateral face, the lateral face comprising a concave portion that isindented or concave in a direction towards the other side frame; and atleast a part of the support member is attached to the concave portion.2. The vehicle seat according to claim 1, wherein: the concave portionextends above an upper end portion of the link member and below a lowerend portion of the link member.
 3. The vehicle seat according to claim1, wherein: the concave portion is provided with an opening and asupport member attachment portion for attaching the support member; andthe opening is disposed at a different height from the support memberattachment portion.
 4. The vehicle seat according to claim 1, wherein:the concave portion is provided with an opening and a support memberattachment portion for attaching the support member; and the opening isdisposed above the support member attachment portion.
 5. The vehicleseat according to claim 1, further comprising: an opening formed in theconcave portion; and a transmission member for transmitting the rearwardmovement of the seat occupant to the headrest; wherein: the transmissionmember overlaps with the opening in a seat right-to-left direction. 6.The vehicle seat according to claim 1, further comprising: an openingformed in the concave portion; and a transmission member fortransmitting the rearward movement of the seat occupant to the headrest;wherein: the transmission member overlaps with the opening in a seatright-to-left direction when the transmission member moves rearward. 7.The vehicle seat according to claim 1, wherein: a connecting plate thatis connected to and located between respective lower portions of theside frames, the connecting plate comprising a projecting curve portionthat projects forward; and the projecting curve portion is larger thanthe rear-end collision detector in length in a seat right-to-leftdirection.
 8. The vehicle seat according to claim 1, wherein: theconcave portion is provided with a support member attachment portion forattaching the support member; and the support member attachment portionis disposed between the front projecting wall and the rear projectingwall.
 9. The vehicle seat according to claim 1, further comprising: atransmission member for transmitting the rearward movement of the seatoccupant to the headrest; wherein: the concave portion is provided withan opening and a support member attachment portion for attaching thesupport member; the opening is disposed at a different height from thesupport member attachment portion and overlaps with the transmissionmember in a seat right-to-left direction; and the support memberattachment portion is disposed between the front projecting wall and therear projecting wall.
 10. A vehicle seat comprising: a seat back framehaving right and left side frames; a headrest forwardly movably mountedto the seat back frame; a rear-end collision detector mounted to theseat back frame, wherein the rear-end collision detector detectsrearward movement of the seat occupant and moves rearward; and therear-end collision detector is operatively connected to the headrestsuch that the rearward movement of the rear-end collision detectorforwardly moves the headrest to support a head of a seat occupant; arespective support shaft mounted to each side frame; a support memberthat supports the support shaft; a link member mounted to the supportshaft; and a biasing member that biases the link member; wherein: alower portion of the link member is connected to the rear-end collisiondetector; each of the side frames is provided with a front projectingwall inwardly projecting and integrally formed at a front end of therespective side frame, and a rear projecting wall inwardly projectingand integrally formed at a rear end of the respective side frame; eachof the side frames comprises a lateral face, the lateral face comprisinga first step portion and a second step portion; and a part of thesupport member is attached between the first step portion and the secondstep portion.
 11. The vehicle seat according to claim 10, wherein: thefirst step portion is disposed above an upper end portion of the linkmember and the second step portion is disposed below a lower end portionof the link member.
 12. The vehicle seat according to claim 10, wherein:an opening is formed at least at a portion of either the first stepportion or the second step portion.
 13. The vehicle seat according toclaim 10, wherein: an opening is formed in the side frame; a supportmember attachment portion for attaching the support member is formedbetween the first step portion and the second step portion; and theopening is disposed at a different height from the support memberattachment portion.
 14. The vehicle seat according to claim 10, wherein:an opening is formed in the side frame; a support member attachmentportion for attaching the support member is formed between the firststep portion and the second step portion; and the opening is disposedabove the support member attachment portion.
 15. The vehicle seataccording to claim 10, further comprising: an opening formed between thefirst step portion and the second step portion; and a transmissionmember for transmitting the rearward movement of the seat occupant tothe headrest; wherein: the transmission member overlaps with the openingin a seat right-to-left direction.
 16. The vehicle seat according toclaim 10, further comprising: an opening formed between the first stepportion and the second step portion; and a transmission member fortransmitting the rearward movement of the seat occupant to the headrest;wherein: the transmission member overlaps with the opening in a seatright-to-left direction when the transmission member moves rearward. 17.The vehicle seat according to claim 10, wherein: a connecting plate thatis connected to and located between respective lower portions of theside frames, the connecting plate comprising a projecting curve portionthat projects forward; and the projecting curve portion is larger thanthe rear-end collision detector in length in a seat right-to-leftdirection.
 18. The vehicle seat according to claim 10, wherein: asupport member attachment portion for attaching the support member isformed between the first step portion and the second step portion; andthe support member attachment portion is disposed between the frontprojecting wall and the rear projecting wall.
 19. The vehicle seataccording to claim 10, further comprising: a transmission member fortransmitting the rearward movement of the seat occupant to the headrest;wherein: an opening and a support member attachment portion forattaching the support member are formed between the first step portionand the second step portion; the opening is disposed at a differentheight from the support member attachment portion and overlaps with thetransmission member in a seat right-to-left direction; and the supportmember attachment portion is disposed between the front projecting walland the rear projecting wall.
 20. A vehicle seat comprising: a seat backframe having right and left side frames; a headrest forwardly movablymounted to the seat back frame; a rear-end collision detector mounted tothe seat back frame, wherein the rear-end collision detector detectsrearward movement of the seat occupant and moves rearward; and therear-end collision detector is operatively connected to the headrestsuch that the rearward movement of the rear-end collision detectorforwardly moves the headrest to support a head of a seat occupant; arespective support shaft mounted to each side frame; a support memberthat supports the support shaft; a link member mounted to the supportshaft; and a biasing member that biases the link member; wherein: alower portion of the link member is connected to the rear-end collisiondetector; each of the side frames is provided with a front projectingwall inwardly projecting and integrally formed at a front end of therespective side frame, and a rear projecting wall inwardly projectingand integrally formed at a rear end of the respective side frame; eachof the side frames comprises a lateral face, the lateral face comprisinga side projecting portion projecting toward a right-to-left direction;and a part of the support member is attached to the side projectingportion.
 21. The vehicle seat according to claim 20, wherein: the sideprojecting portion extends above an upper end portion of the link memberand below a lower end portion of the link member.
 22. The vehicle seataccording to claim 20, wherein: the side projecting portion is providedwith an opening and a support member attachment portion for attachingthe support member; and the opening is disposed at a different heightfrom the support member attachment portion.
 23. The vehicle seataccording to claim 20, wherein: the side projecting portion is providedwith an opening and a support member attachment portion for attachingthe support member; and the opening is disposed above the support memberattachment portion.
 24. The vehicle seat according to claim 20, furthercomprising: an opening formed in the side projecting portion; and atransmission member for transmitting the rearward movement of the seatoccupant to the headrest; wherein: the transmission member overlaps withthe opening in a seat right-to-left direction.
 25. The vehicle seataccording to claim 20, further comprising: an opening formed in the sideprojecting portion; and a transmission member for transmitting therearward movement of the seat occupant to the headrest; wherein: thetransmission member overlaps with the opening in a seat right-to-leftdirection when the transmission member moves rearward.
 26. The vehicleseat according to claim 20, wherein: a connecting plate that isconnected to and located between respective lower portions of the sideframes, the connecting plate comprising a projecting curve portion thatprojects forward; and the projecting curve portion is larger than therear-end collision detector in length in a seat right-to-left direction.27. The vehicle seat according to claim 20, wherein: the side projectingportion is provided with a support member attachment portion forattaching the support member; and the support member attachment portionis disposed between the front projecting wall and the rear projectingwall.
 28. The vehicle seat according to claim 20, further comprising: atransmission member for transmitting the rearward movement of the seatoccupant to the headrest; wherein: the side projecting portion isprovided with an opening and a support member attachment portion forattaching the support member; the opening is disposed at a differentheight from the support member attachment portion and overlaps with thetransmission member in a seat right-to-left direction; and the supportmember attachment portion is disposed between the front projecting walland the rear projecting wall.
 29. A vehicle seat comprising: a seat backframe having right and left side frames; a headrest forwardly movablymounted to the seat back frame; a rear-end collision detector mounted tothe seat back frame, wherein the rear-end collision detector detectsrearward movement of the seat occupant and moves rearward; and therear-end collision detector is operatively connected to the headrestsuch that the rearward movement of the rear-end collision detectorforwardly moves the headrest to support a head of a seat occupant; arespective support shaft mounted to each side frame; a support memberthat supports the support shaft; a link member mounted to the supportshaft; a biasing member that biases the link member; a flexible platemember disposed in front of the rear-end collision detector; a seat backcushion provided in front of the flexible plate member; and a pressureadjusting mechanism for pushing the seat back cushion to a frontdirection by forwardly protruding the flexible plate member that resultsfrom the flexible plate member being bent; wherein: a lower portion ofthe link member is connected to the rear-end collision detector; each ofthe side frames is provided with a front projecting wall inwardlyprojecting and integrally formed at a front end of the respective sideframe, and a rear projecting wall inwardly projecting and integrallyformed at a rear end of the respective side frame; each of the sideframes comprises a lateral face, the lateral face comprising a concaveportion that is indented or concave in a direction towards the otherside frame; at least a part of the support member is attached to theconcave portion; the concave portion extends above and below the supportshaft; and an upper end of the flexible plate member is disposed above acentral axis point of the support shaft.
 30. The vehicle seat accordingto claim 29, further comprising: a transmission member for transmittingthe rearward movement of the seat occupant to the headrest; wherein: theconcave portion is provided with an opening and a support memberattachment portion for attaching the support member; the opening isdisposed at a different height from the support member attachmentportion and overlaps with the transmission member in a seatright-to-left direction when the transmission member moves rearward; andthe support member attachment portion is disposed between the frontprojecting wall and the rear projecting wall.
 31. The vehicle seataccording to claim 29, wherein: a connecting plate that is connected toand located between respective lower portions of the side frames, theconnecting plate comprising a projecting curve portion that projectsforward; and the projecting curve portion is larger than the rear-endcollision detector in length in a seat right-to-left direction.
 32. Avehicle seat comprising: a seat back frame having right and left sideframes; a headrest forwardly movably mounted to the seat back frame; arear-end collision detector mounted to the seat back frame, wherein therear-end collision detector detects rearward movement of the seatoccupant and moves rearward; and the rear-end collision detector isoperatively connected to the headrest such that the rearward movement ofthe rear-end collision detector forwardly moves the headrest to supporta head of a seat occupant; a respective support shaft mounted to eachside frame; a support member that supports the support shaft; a linkmember mounted to the support shaft; a biasing member that biases thelink member; a flexible plate member disposed in front of the rear-endcollision detector; a seat back cushion provided in front of theflexible plate member; a pressure adjusting mechanism for pushing theseat back cushion to a front direction by forwardly protruding theflexible plate member that results from the flexible plate member beingbent; and a wire member that supports the flexible plate member;wherein: a lower end portion of the link member is connected to therear-end collision detector; each of the side frames is provided with afront projecting wall inwardly projecting and integrally formed at afront end of the respective side frame, and a rear projecting wallinwardly projecting and integrally formed at a rear end of therespective side frame; each of the side frames comprises a lateral face,the lateral face comprising a concave portion that is indented orconcave in a direction towards the other side frame; at least a part ofthe support member is attached to the concave portion; the concaveportion is disposed between the front projecting wall and the rearprojecting wall, and extends above and below the support shaft andextends above an upper end portion of the link member and below thelower end portion of the link member; an upper end of the flexible platemember is disposed above a central axis point of the support shaft; thewire member is connected to a lower portion of the seat back frame; aconnecting plate that is connected to and located between respectivelower portions of the side frames, the connecting plate comprising aprojecting curve portion that projects forward; and the projecting curveportion is larger than the rear-end collision detector in length in aseat right-to-left direction.
 33. The vehicle seat according to claim32, further comprising: a transmission member for transmitting therearward movement of the seat occupant to the headrest; wherein: theconcave portion is provided with an opening and a support memberattachment portion for attaching the support member; the opening isdisposed at a different height from the support member attachmentportion and overlaps with the transmission member in a seatright-to-left direction when the transmission member moves rearward; andthe support member attachment portion is disposed between the frontprojecting wall and the rear projecting wall.